Agriculture Reference
In-Depth Information
a
b
ALFALFA
MAIZE
35
30
9 mm
7 mm
80
12 mm
5 mm
70
3 mm
25
60
20
50
8
15
25
15
10
mm
40
30
50
90
130
CAPACITY (t/h)
170
210
250
150
200 250 300 350 400
CAPACITY (t/h)
Fig. 5.12
Power required at PTO and capacity as affected by cutting length for alfalfa (
a
) and
maize (
b
). Adapted from [
21
]
• Row crop: Row-crop heads are usually used to harvest corn or sorghum and are
generally available in one to six row sizes and with different row widths. The
gathering chains or belts grab the cut stalks and feed them into the feed rolls.
The belts are more efficient in the lodged crops. Some row-independent heads
are also available, which permit harvesting independent of row width and they
are also effective for the lodged crop.
• Ear-corn snapper: Ear-corn snapper heads are similar to corn heads for combines
and are equipped with two counter rotating rolls which pull stalks through snap-
ping bars under the gathering chains to snap off the ears. Gathering chains carry
the ears back to a cross auger which conveys corn to the cutterhead for chopping.
The energy consumption is dependent on the crop and its dry matter content,
length of cutting, sharpness of the knives, and distance between the knives and fixed
shearbar.Typicalenergyrequirementvariesfrom2to3.0kWht
−1
. The PTO power
requirement as affected by the cutting length is shown in Fig.
5.12
.
5.3.4
Collection and Densification
After biomass is cut or chopped, an important process that follows is collection and
densification. For dry energy crops, baling is the most common method of densifica-
tion. For chopped biomass, processes of either cut-and-throw or cut-and-blow are
typically employed.
5.3.4.1
Baling
Balers are designed to produce either round bales or rectangular bales. The size of
rectangular bales falls into small and large categories. For bioenergy crops, large
rectangular balers or large round balers are most commonly used. Round bales are
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